TUESDAY, March 10, 2015 (HealthDay News) -- Depression may increase the risk of poor nutrition and obesity among Americans receiving food assistance, a new study suggests.

The researchers looked at more than 600 people who were the main food shoppers in low-income families living in "food deserts" in Pittsburgh. The term refers to neighborhoods with limited access to healthy foods, such as fresh produce. All of the participants were enrolled in a food assistance program.

There was a strong link between depression, poor nutrition and high body-mass index (BMI) -- an estimate of body fat based on height and weight, according to the study in the March 10 issue of the Journal of the Academy of Nutrition and Dietetics.

However, the research did not prove that depression was a cause of bad eating habits or obesity.

"This study focuses on a group that is of particular importance: low-income, primarily African-American residents of urban food deserts," lead investigator Karen Florez, an associate social scientist at the Rand Corp., said in a journal news release.

"This group is at particularly high risk of obesity and poor nutrition," she added. "Thus, the finding that depression is associated with even higher risk within this already high-risk group suggests a potential avenue for intervention is a focus on mental health."

Previous research has shown that lower-income Americans have higher obesity rates, the researchers noted. For example, 42 percent of low-income women are obese, compared with 29 percent of women who live well above the poverty line.

And while being enrolled in a food-assistance program improves access to food, some studies suggest that people in such a program consume less fruit, more sugar-sweetened beverages, more total fat and added sugars, and more excess calories than those who don't receive food assistance, the researchers noted.

Further research is needed to determine if eating a healthier diet and controlling weight may improve mental health in this group of people, Florez added.